Scuba ("self-contained under water breathing apparatus") diving is becoming an ever more popular pursuit. In addition, its commercial applications are becoming more extensive and varied. However, it is appreciated that there is an element of risk in scuba diving and, indeed, many of the training courses available accentuate the safety aspects of the pursuit. It has, therefore, become well established to use the so-called "buddy" system in which divers dive in pairs so that, at all times, they have someone to turn to in the event of an emergency. For instance, if one diver's breathing apparatus becomes faulty, he can share the air of the other diver using well established procedures.
However, the "buddy" system relies upon the fact that the two divers can, in some way, communicate with each other. Normally, the communication is carried out by a series of agreed hand signals or using an underwater writing slate. This system of communication suffers from the disadvantage that it relies almost entirely upon the divers remaining within sight of each other. Where the water is unclear, for instance around the British Isles or if a wreck is being dived, unless great care is taken divers can often loose sight of each other which can result in the effective breakdown of the "buddy" system and a substantial increase in the inherent risk involved. However this danger has been recognised for some years and a number of proposals have been put forward in an attempt to overcome the problem.
United Kingdom patent application number GB 2 133 599 discloses a monitoring system for divers in which ultra acoustic signals are transmitted continuously on a predetermined frequency to a monitoring station provided on a surface escort vessel. The system generates a periodic test signal which has to be acknowledged by the diver. If no response signal is generated, the frequency of the transmission signals is increased and an alarm is generated in the monitoring station. However, this system requires there to be a third party involved in the monitoring and does not, in particular, enhance the reliability or safety of the "buddy" system. Further, although it is an expensive system to operate, it provides only an emergency signal.
Proposals have been put forward for voiced communication between two or more scuba divers. However, such a system is expensive and complicated. It needs to enable the diver to speak relatively clearly and be able to breathe which requires modifications to the standard breathing apparatus and also complex signalling systems to deal with voiced transmissions. No such voiced communication system has, in practice, established itself in the market place.
It is an object of the present invention to provide a novel and inventive communication apparatus for diver to diver communication.